A memory device having a three-dimensional structure has been proposed in which a memory hole is made in a stacked body in which multiple electrode layers are stacked, and a charge storage film and a semiconductor film are provided to extend in the stacking direction of the stacked body inside the memory hole. The memory device includes multiple memory cells connected in series between a drain-side selection transistor and a source-side selection transistor. The electrode layers of the stacked body are gate electrodes of the drain-side selection transistor, the source-side selection transistor, and the memory cells. A slit that reaches a substrate from the upper surface of the stacked body is made in the stacked body. A conductor is filled into the slit. For example, the conductor is used to form a source line. The aspect ratio of the cross section of the slit along the minor-axis direction is large. Therefore, it is difficult to pattern the slit perpendicularly from the upper surface of the stacked body to the substrate. The width in the minor-axis direction of the slit becomes narrower in the lower layer portion (the substrate side) of the stacked body and wider in the upper layer portion (the upper surface side of the stacked body). Accordingly, the planar surface area of the electrode layer becomes wider in the lower layer portion of the stacked body and narrower in the upper layer portion of the stacked body. Thereby, a difference between the resistance values of the electrode layers of the stacked body occurs. It is desirable for the difference between the resistance values of the electrode layers to be small.